1. Field of Invention
This invention relates to a method for treating aqueous solutions of sugars and proteins to obtain non-hygroscopic solids. In one aspect, the invention relates to a dry pet food, useful as a dog treat, and to solid animal feed supplements.
2. Brief Statement of Prior Art
Aqueous solutions of sugars and/or proteins are commonly produced as by-products of the food industry. Typical of these are cane molasses and beet molasses which are produced as by-products of the sugar industry. Citrus molasses is a by-product of fruit juice concentrate manufacture. Wood molasses is a by-product of the pulp and paper industry. Corn syrup and corn steep liquor, which is high in protein, are produced during processing of corn. Whey is a by-product of cheese manufacture. The aforementioned solutions are usually concentrated for more efficient and economical handling.
The degree of concentration, i.e., solids content, which is commonly achieved is variable and depends on the particular solution. Thus, cane and beet molasses and corn syrup are commonly produced and handled at 75 to 80 percent solids while citrus and wood molasses contain about 50 percent solids. Whey, condensed molasses solubles and corn steep liquor are also usually concentrated to about 50 percent solids.
The shipping and storage of these solutions thus entails shipping and handling a considerable weight and volume of water. Additionally, the water activity of these solutions is usually sufficiently high to permit microbial growth, and precautions in handling, and addition of preservatives, are necessary to prevent spoilage.
The difficulties and expenses encountered in handling and storing of these concentrated aqueous solutions has prompted efforts to dry the liquids to solids. Cane molasses and whey have been dried, however, the processes are complex and costly, often requiring two or more steps and conoluding with spray drying. Additionally, the solids which are obtained are quite hygroscopic and precautions must be taken to keep the solids dry, or in sealed containers. These disadvantages have confined dried molasses and whey solids to very limited, specialized markets.
The aforementioned solutions of sugars and/or proteins are frequently used in animal feeds. The costs incurred to dry these solutions and the handling and storing precautions for the dried solids have, heretofore, precluded use of the dried solids for animal feeds. Instead, the concentrated solutions are used directly in liquid blends with other feed ingredients such as protein meals, fats, minerals and vitamins. Molasses has been dried on a solid carrier such as soybean hulls or pressed oil cake to prepare a dry animal feed supplement. Since the solid carrier is used in amounts up to equal weights with the molasses, no concentration of the molasses is achieved; instead, a solid carrier is substituted for water. This product has a limited market which is confined to farms and ranches which lack equipment to handle molasses.
In the past decade, these solutions have also been gelled into animal feed blocks by the addition of calcium oxide, or hydroxide, and a soluble phosphate in the manner described in U.S. Pat. No. 4,027,043. Since the gelling additives and other feed ingredients are added batchwise and the resulting mixture is poured into boxes or molds, the products have become known as poured molasses blocks. These blocks have found widespread use for range cattle feeding as sources of energy, minerals and vitamins. Other applications have included supplement feeding of horses, sheep and dairy cattle. The blocks have been produced and marketed in various sizes from 40 pounds to one ton, and the most popular size currently being 250 pounds. The water contents of the gelled solids are from 25 to about 35 weight percent, although some experimental poured blocks have been obtained with only 22 weight percent water and as high as 40 weight percent water. The substantial water content of these blocks has generated problems. It is usually necessary to add preservatives and to exercise precautions in handling and storing of the blocks to avoid spoilage. The blocks are also cumbersome and bulky, and are not as easily handled as are bulk quantities of granular solids.
In a related process, molasses is concentrated by evaporation under a vacuum to a very low water content, and dry animal feed solids such as protein meals, vitamins and minerals are added before the concentrated molasses solidifies. In commercial practice, the solid product is quite hygroscopic and must be stored and handled in metal or plastic barrels.
In my prior U.S. Pat. No. 4,643,908, I disclose that a soft and moist dog food can be prepared from approximately equal parts water, inverted whey and a meat meal. These ingredients are gelled to obtain a solid which is highly palatable and nutritious. The product, however, is tacky and has a crumbly texture, and is thus difficult to store and handle.